Incontinence is a prevalent problem in many contexts. These contexts include nursing homes, acute care facilities, and intensive care units (ICUs). Incontinent patients have long been wrapped in diapers. Continued contact of the skin with body waste leads to Incontinence-Associated Dermatitis (IAD), known familiarly as “diaper rash.” IAD can further develop into pressure ulcer (PU) and other secondary skin infections. According to Changing Our Methods of Adult Incontinence Management to Decrease Skin Breakdown and Improve Patient Satisfaction, 42nd Wound, Ostomy & Continence Nurses Society Conference, Jun. 12-16, 2010, 78% of acute-care hospitalized adult patients wearing diapers suffered from these conditions.
Major metropolitan hospitals are now banning diapers in favor of underpads because of the associated dermatological effects. Incontinence hospital patients are now placed on underpads while wearing open-back gowns. Underpads, which are multilayer pads, are preferable to diapers in that the contact area between waste and skin is minimized. Changing of an underpad is quite simple in comparison to changing a diaper.
Many approaches have been taken in the prior art to provide a sensor embedded in a multilayer absorbent article in order to indicate an incontinence event. In this manner, a patient can be attended to when there is a need rather than on a predetermined time schedule. Prior approaches have been embodied primarily in diapers. A number of these approaches utilize radio frequency (RF) resonance, and recently, radio frequency identification (RFID) incorporating advances in this technology. RFID is familiar to consumers as the technology that permits vehicle owners of RFID identification devices to bypass toll booths and enter secured garages without stopping. RFID offers added identification capability to RF resonance. User and usage data can now be recorded and retrieved wirelessly. Most RFID systems are continuously powered, not unlike cellular network systems in their quest for RFID tags or cell phones to be identified by the systems to fulfill requests for action. In view of recent government reports of continuous cell phone usage causing brain diseases, an RFID system that does not require continuous radio frequency query could mitigate this undesirable side effect.
An RFID tag primarily comprises an antenna. A passive tag is not powered; but when its antenna resonates with a signal generated by its mating controller-transceiver, the energy received powers on the tag integrated circuit to activate the tag. Passive RFID tags can be queried via a frequency with which the antenna is resonant. In response to excitation with a resonant frequency, the resonating antenna provides energy which can be stored in a capacitor, for example. Many variations of this arrangement are provided. Passive RFID tags are more convenient to use than active (powered) RFID tags. They do not depend on battery or external power to work and are suitable for reporting incontinence conditions wirelessly. Generally prior art using RFID tags do not take advantage of their “ID” capability, and only to identify tags for action sequencing purposes. Most use the tags because of their compactness and ease of use attributes. The RFID tags provide a binary output in effect. While the identification may reside in many bits of information, the end result is always confirmation of an authorized response, affirmative or not. The binary output is effective to provide acknowledgement to indicate a “wet” condition or absence of a wet condition.
United States Published Patent Application No. 20020145525 discloses a diaper comprising a plurality of RFID tags. Each of the RFID tags is coated with a dry electrolyte which enhances response to moisture. Each tag is also assigned a unique frequency. The sequence and relative response of tags to enquiring signals indicate position and moisture status. Because of the design complexity, implementation can be costly.
United States Published Patent Application No. 20140358099 discloses a system embedded in a diaper including first and second RFID tags respectively placed on an upper end and a lower end of a diaper with a moisture strip connected to both tags. This construction requires special fabrication to connect the RFID tags and the sensor. Standard, off-the-shelf components cannot be used.
U.S. Pat. No. 8,502,684 discloses a diaper with dissolvable conductive moisture sensor traces connected to an RFID tag antenna. Initial moisture contact will not completely dissolve the traces, and an antenna impedance change will indicate an initial moisture. A positive incontinence condition is indicated by complete dissolution of the traces, with the RFID antenna not functioning. Lack of response is indistinguishable from a complete failure. Special materials must be used for the conductive traces to avoid breaks during handling and in in situ wearing conditions
U.S. Pat. No. 6,876,303 discloses a system for monitoring hospital personnel, a plurality of patient locations for patients and associated devices having a plurality of patient controls. Transmitters carried by each of a plurality of hospital personnel each periodically transmit a signal unique to that transmitter. The signal could indicate a patient or sensor triggered event alarm. A computer coupled to the associated devices is configured to respond to disable at least one of the patient controls while hospital personnel attend to the patient. This arrangement monitors hospital personnel and not patients nor their need status.
U.S. Pat. No. 8,237,572 and other patents, including U.S. Pat. No. 8,248,249 disclose an RFID tag and a system and method involving a plurality of RFID tags. Each RFID tag is attached to an object or to a structure or a person on which the presence of a predefined fluid is monitored. In a first state, absence of the monitored fluid, the tag is acting as a passive RFID tag and the information it holds can be read with a proximity RFID reader. This operation is performed when the RFID tag is attached to the object to be monitored. At this stage a table associating tag ID, object name and location may be built, and may be recorded so that information it contains is accessible by a control center. In a second state, whenever the monitored fluid appears on the tagged object, a fluid activated battery generates the electrical power which is used to power the RFID tag. The RFID tag then acts as an active RFID tag and starts to emit messages which can be received by a distant RFID reader. Alert messages include at least the tag ID but may comprise additional information like a name or a location. This method relies on activation of a battery by waste fluid. This is a nonconventional component.
U.S. Pat. No. 8,196,809 discloses a system including a reader and an absorbent article containing machine-readable information identifying the user associated with the absorbent article and the user's location. A computer uploads data from the reader and stores the identifying information. On retrieval of information from the computer memory, information concerning the absorbent article is automatically associated with the identity and location of a user of the absorbent article. This patent is only concerned with inventory of the absorbent article, and no live usage condition sensing is involved. This arrangement does not provide the benefit of monitoring the in situ status of the incontinence article as well as identification of its user and location.